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THE LASER1 TODAY AND TOMORROW

The laser has become a multipurpose tool. It has caused a real revolution in technology.

Atoms emit rays of different length, which prevents the forming of an intense beam of light. The laser forces its atoms to emit rays having the same length and travelling in the same direction. The result is a narrow, extremely intense beam of light that spreads out very little and is therefore able to travel very great distances.

The most common laser is the helium-neon laser in the laser tube, containing 10 per cent helium gas and 90 per cent neon gas. At the end of the tube there is a mirror, and at the other end there is a partial mirror[2]. The electrons get energy from a power supply[3] and become "excited", giving off energy as light. This tight is reflected by the mirror at one end of the tube. It can only escape through the partial mirror at the other end of the tube.

The first laser was built in I960. Since then scientists have developed several types of the laser which make use of luminescent crystals, luminescent glass, a mixture of various gases and finally semiconductors.

Having been developed at Lebedev Institute of Physics in 1962, semiconductor quantum generators occupy a special place among the optical generators. While the size of the ruby crystal laser comes to tens of centimetres and that of the gas generator is about a metre long, the semiconductor laser is a few tens of a millimetre long, the density of its radiation being hundreds of thousands of times greater than that of the best ruby laser.

But the most interesting thing about the semiconductor laser is that it is able to transform electrical energy directly into light wave energy. With an efficiency approaching 100 per cent as compared to a maximum of about 1 per cent of other types, the semiconductor laser opens up new possibilities of producing extremely economical sources of light.

But it is in the field of communication that the laser will find its most extensive application in future. Scientists foresee the day when a single laser beam will be employed to cany simultaneously millions of telephone conversations or a thousand of television programmes. It will serve for fast communications across continents, under the sea, between the Earth and spaceships and between men travelling in space.

The potential importance of these applications continues to stimulate new development in the laser field.

Ответьте на вопросы.

1. What is the laser?

2. What is the function of the laser?

3. What beam of plight does the laser produce?

4. When was the first laser built?

5. What types of quantum generators did scientists develop after I960?

6. What type of the laser is the most common one at present?

7. Where will the laser find the most extensive applications in future?

Контрольная работа 4

Вариант 2

Выполните письменно следующие упражнения.

1. Переведите предложения, обращая внимание на перевод герундия.

A. Using radioactive isotopes opens up new possibilities for medicine and agriculture.

B. The Curies' having discovered radium gave them the possibility of discovering other radioactive elements.

C. We know of the atomic reactor being fed with uranium 235.

D. We know of Yablochkov's having found a brilliant solution to the difficult problem of using the electric arc for lighting.

E. Work on "braking" the H-bomb and on using the fusion process for generating electricity is going forward in several countries.

Переведите предложения. Обратите особое внимание на перевод усилительной конструкции.

A. It was after solving the problem of splitting the nuclei of some elements that the atomic energy could be received.

B. It was Kurchatov who discovered the isomerism of artificial radioactive nuclei.

А) определите форму причастия в предложении; б) предложения переведите.

A. Using isotopes in measuring the diffusion of metals we got much more accurate data.

B. Scientists have found a simple way to produce a laser beam of any colour and frequency desired.

C. Being produced by the laser the narrow intense beam travels great distances without spreading.

D. Having reached the surface of the Moon, it returned to the Earth three seconds later, its return being recorded by sensitive devices.

А) определите форму инфинитива в предложении; б) предложения переведите.

A. The traditional approach to this problem is to consider each new process as a new problem.

B. Scientists make new electronic machines store information, handle calculations and even control production processes.

C. Digital computers are likely to be wider used than analogue ones.

D. Plastics are supposed to be used instead of metals in many cases.

E. Tidal forces are expected to make considerable contribution if not to present day, at least to future electricity production.

F. It takes much time for the reaction to complete at a low temperature.

G. Newton was the first to realize elliptical paths of comets.

H. It required some more experiments for the engineer to prove the precision of the results obtained.

I. The computing equipment enabled investigators to process the received data much quicker.